Objective:
To determine how often trophectoderm biopsy and rapid, real-time quantitative polymerase chain reaction (PCR)-based comprehensive chromosome screening (CCS) alters clinical management by resulting in the transfer of a different embryo than would have been chosen by traditional day 5 morphology-based criteria.

Design:
Prospective.

Setting:
Academic center for reproductive medicine.

Patient(s):
Infertile couples (n = 100; mean age 35 ± 4 years) with at least two blastocysts suitable for biopsy on day 5.

Intervention(s):
Prior to trophectoderm biopsy for CCS the embryologist identified which embryo would have been selected for traditional day 5 elective single ET.

Main Outcome Measure(s):
The risk of aneuploidy in the embryos that would have been selected on day 5 was calculated and compared with the aneuploidy rate of the cohort of all embryos that underwent CCS testing. The aneuploidy risk was compared between age groups.

Result(s):
After quantitative PCR-based CCS, 22% (95% confidence interval 15%–31%) of the embryos selected by day 5 morphology were aneuploid, which was lower than the 32% aneuploidy rate of the cohort. Patients ≥35 years had a higher risk of an aneuploid blastocyst being selected by morphology than those <35 years old (31% vs. 14%). Among patients who had selection altered by CCS, 74% (14/19) delivered, including 77% (10/13) after elective single ET. Most patients (77%) had an additional euploid blastocyst vitrified for future use.
Conclusion(s):
The CCS results alter embryo selection due to the presence of aneuploidy in embryos with optimal day 5 morphology. Excellent outcomes were obtained when CCS-based selection was different than morphology-based selection.

Congratulations on a well-designed study suggesting that comprehensive chromosome screening (CCS) alters embryo selection over selection based on morphology alone, and that it may thereby improve outcomes. One obstacle to widespread use of CCS will be the significant added cost- as the authors point out ICSI and assisted hatching are recommended in this setting, potentially increasing the cost beyond that of PGS alone.

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